26 ON THE CLASSIFICATION OP BIRDS. 
part of all these divisions of the foot are more or less 
defended by scales. Some ornithologists term the anterior 
or fore part of the tarsus, acrotarsum, and the hind part, 
planta; and hence we find, in generic characters, acro- 
tarmm scutulatum. But this character is altogether su- 
perfluous, since it is one of the most universal in the class 
of Aves ! Out of thousands of birds which we have seen, 
not one has lieen met with, whose tarsi, if naked, were 
not protected in front by scales ; and even the very few 
that are booted, or clothed with feathers in this part, 
have scales upon the front of their toes. This is suf- 
ficiently apparent among many of the owls, the buzzards, 
and the ptarmigans. Thus far for the nomenclature of 
birds, which, however dry, must be learned by every 
student. \Te shall now trace in what manner these 
several parts are found to vary. 
(34.) We have already remarked that a bird, like 
most other animals, is composed of three parts : 1 , Head ; 
2. Body ; and, 3. Members, or Limbs. Life is soon 
extinguished if the first or second is in any degree 
mutilated ; but a slight injury to the limbs is not at- 
tended witli such fatal consequences. Nature herself 
repairs the wound, if it is not too severe to prevent the 
bird from procuring its food. We have seen a toucan, 
whose bill bore evident marks of having been shot 
through, and even fractured, long before the bird met 
its ultimate fate ; while the wings and legs of other 
birds have been found injured and healed in a similar 
manner. 
(35.) The parts of the head comprise the eyes, ears, 
nostrils, and mouth; to the last of which belong the bill 
and tongue. The head itself is sometimes remarkably 
large, as in the owls, for the purpose of containing cer- 
tain chambers, or cavities, connected with an unusual 
development of the sense of hearing : this adiUtional 
faculty given to the birds in question, is highly advan- 
tageous to their nocturnal search after food ; and it is 
very probable that the superior size of the head which 
so often distinguishes other fissirostral types, as the 
